Piston sealing ring apparatus

Abstract

A sealing ring device is provided for a fluid valve having a piston (2) reciprocating within a cylinder (1), wherein the piston (2) includes a valve cone (2c) adapted to contact a valve seat (11). In order to seal the inner space of the cylinder (1) located behind the piston (2) from an inlet/outlet passageway (A), a resilient sealing ring (5) is disposed in an annular groove (4) opening into the cylinder (1) around the rear end (2a) of the piston (2). A press ring (7), which extends above the rear end (2a) of the piston (2), contains the sealing ring (5) in the annular groove (4). A spring element (8) rests on the press ring (7). A piston rod (3) is guided in slidable manner through the piston (2). A stop (9) is attached to the rod (3) above the rear end (2a) and opposite the top side of the spring element (8). Downward movement of the rod (3) past the end position of piston (2) causes the stop (9) to compress the spring element (8), and the resulting force is transferred by the press ring (7) to the sealing ring (5) to expand the sealing ring (5) against the piston (2) and the cylinder (1).

We claim: 
     
       1. A sealing apparatus for a piston slidably disposed within a cylinder, comprising: a piston rod extending axially and slidably through the piston, said piston rod having reciprocating axial motion;   an annular groove extending around a first end of the piston and opening into the cylinder;   a resilient sealing ring disposed within said annular groove between the piston and the cylinder;   a press ring disposed within said annular groove to contain said sealing ring in said annular groove, said press ring extending beyond said first end of the piston;   a first stop being in engagement with said piston rod at a predetermined distance from said first end of the piston; and   a resilient means connected between said first stop and said press ring, said first stop being movable by the piston rod in a direction toward said first end of said piston whereby a portion of said resilient means engages a top portion of said press ring for biasing said press ring against said sealing ring in said annular groove in only one direction of piston movement for increasing the sealing force of said sealing ring between the piston and the cylinder.   
     
     
       2. The sealing device of claim 1, further comprising a second stop rigidly attached to said piston rod at a second end of the piston. 
     
     
       3. The sealing device of claim 2, wherein said biasing means comprises an annular disk spring having an inner rim connected to said first stop and an outer rim contacting said press ring. 
     
     
       4. The sealing device of claim 3, further comprising: a valve having a valve seat; and   a valve cone disposed around said second end of the piston for contacting said valve seat to close said valve.   
     
     
       5. The sealing device of claim 4, wherein said axial motion of said piston rod toward said second end forces said valve cone against said valve seat and compresses said spring, thereby applying pressure to said press ring to expand said sealing ring. 
     
     
       6. The sealing device of claim 5, wherein said spring applies pressure to said press ring only when said valve is closed by said valve cone. 
     
     
       7. The sealing device of claim 5, wherein: said first stop includes a first axial duct;   the piston includes a second axial duct; and   said first and second ducts provide pressure equalization between the cylinder and said second end of the piston.   
     
     
       8. A sealing apparatus for a fluid valve, comprising: a piston slidably disposed within a cylinder, said piston having a valve cone for closing said valve by contacting a valve seat;   a piston rod extending axially and slidably through said piston and having a first stop being in engagement with said rod at a predetermined distance from a first end of said piston and a second stop rigidly attached to said rod at a second end of said piston, said piston rod having reciprocating axial motion;   an annular groove extending around said first end of said piston and opening into said cylinder;   a resilient sealing ring disposed within said annular groove between said piston and said cylinder;   a press ring disposed within said annular groove to contain said sealing ring in said annular groove, said press ring extending beyond said first end of said piston; and   a resilient means connected between said first stop and said press ring, said first stop being movable by the piston rod in a direction toward said first end of said piston whereby a portion of said resilient means engages a top portion of said press ring for biasing said press ring against said sealing ring in said annular groove in only one direction of piston movement for increasing the sealing force of said sealing ring between the piston and the cylinder.   
     
     
       9. The sealing device of claim 8, wherein said biasing means comprises an annular disk spring having an inner rim connected to said first stop and an outer rim contacting said press ring. 
     
     
       10. The sealing device of claim 9, wherein said axial motion of said piston rod toward said second end forces said valve cone against said valve seat and compresses said spring, thereby applying pressure to said press ring to expand said sealing ring. 
     
     
       11. The sealing device of claim 10, wherein said spring applies pressure to said press ring only when the valve is closed by said valve cone. 
     
     
       12. The sealing device of claim 10, wherein: said first stop includes a first axial duct;   said piston includes a second axial duct; and   said first and second ducts provide pressure equalization between said cylinder and said second end of said piston.   
     
     
       13. A sealing apparatus for a fluid valve having a piston slidably disposed within a cylinder, comprising: a piston rod extending axially and slidably through the piston and having a first stop being in engagement with said rod at a predetermined distance from a first end of the piston and a second stop rigidly attached to said rod at a second end of the piston, said piston rod having reciprocating axial motion;   an annular groove extending around said first end of the piston and opening into the cylinder;   a valve cone disposed around said second end of the piston for contacting a valve seat to close the valve;   a resilient sealing ring disposed within said annular groove between the piston and the cylinder;   a press ring disposed within said annular groove to contain said sealing ring in said annular groove, said press ring extending beyond said first end of the piston; and   a resilient means connected between said first stop and said press ring, said first stop being movable by the piston rod in a direction toward said first end of said piston whereby a portion of said resilient means engages a top portion of said press ring for biasing said press ring against said sealing ring in said annular groove, wherein said axial motion of said piston rod toward said second end forces said valve cone against said valve seat and forces said biasing means to apply pressure to said press ring to expand said sealing ring between the piston and the cylinder only during movement of said valve cone in a closing direction.   
     
     
       14. The sealing device of claim 13, wherein said biasing means comprises an annular disk spring having an inner rim connected to said first stop and an outer rim contacting said press ring. 
     
     
       15. The sealing device of claim 14, wherein said spring applies pressure to said press ring only when the valve is closed by said valve cone. 
     
     
       16. The sealing device of claim 13, wherein: said first stop includes a first axial duct;   the piston includes a second axial duct; and   said first and second ducts provide pressure equalization between the cylinder and said second end of the piston.